These substances are injected into the body, and are usually tagged with a radioactive atom, such as Carbon-11, Fluorine-18, Oxygen-15, or Nitrogen-13, that has a short decay time. These radioactive atoms are formed by bombarding normal chemicals with neutrons to create short-lived radio...
The neutrinos used in this analysis were mostly produced when hydrogen or heavier nuclei from high-energy cosmic rays, created outside the solar system, interacted with nitrogen or oxygen nuclei in the Earth's atmosphere. This creates a cascade of particles, including several types of subatomic pa...
These substances are injected into the body, and are usually tagged with a radioactive atom, such as Carbon-11, Fluorine-18, Oxygen-15, or Nitrogen-13, that has a short decay time. These radioactive atoms are formed by bombarding normal chemicals with neutrons to create short-lived radio...
Normal atoms are made up of protons and neutrons in the nucleus (see How Atoms Work), surrounded by a cloud of electrons. In plasma, the electrons separate from the nucleus. Once the energy of heat releases the electrons from the atom, the electrons begin to move around quickly. The ...
Establishing a human presence on Mars will be risky, but researchers are finding solutions that will keep future residents alive long enough to die peacefully.
This may vary, as one element, including carbon, may have different isotopes — forms of the element with different numbers of neutrons, and thus, different masses. The atomic mass shown on the periodic table is an average based on how common different isotopes are in relation to each other...
When the renowned cosmologist Carl Sagan declared that "we are made of starstuff," he wasn't speaking metaphorically. As Sagan said in the TV series "Cosmos," many of the elements in our bodies - "the nitrogen in our DNA, the calcium in our teeth, the iron in our blood" - were for...
Ionizing radiation sensors measure ionizing radiation (alpha, beta or gamma rays) or neutrons. We use ionizing radiation in nuclear reactors and nuclear weapons. But they can also occur naturally. The primary sources of this ionizing radiation are cosmic rays. They come from deep space and radon...
Two helium-3 atoms combine to form a helium-4 atom (two protons and two neutrons) and two protons. These reactions account for 85 percent of the sun's energy. The remaining 15 percent comes from the following reactions: A helium-3 atom and a helium-4 atom combine to form a beryllium-...
This simple atom consists of a nucleus (containing the protons and neutrons) and an electron cloud. It's helpful to think of the electrons in this cloud circling the nucleus in many different orbits. Absorbing Energy Absorption of energy: An atom absorbs energy in the form of heat, light ...